The present invention relates to a beam structure in a pulp machine, paper machine, board machine or a paper/board finishing device.
With regard to the prior art, reference is made to the following publications FI 925655 and DE G 91 13 542.7.
Thus, composite beam structures of a paper machine are known from the prior art. The doctor beam in one prior-art arrangement is a structure having a triangular cross-section and comprises corner pieces to which side plates are attached. The side plates are advantageously made of a composite material. Nonetheless, prior art structures have certain inherent limitations and shortcomings.
Accordingly, it is an object of the present invention to provide an improved composite beam structure for use in a paper machine, board machine or paper/board finishing device.
It is another object of the present invention to provide an improved composite beam structure that is simple in construction and inexpensive to manufacture.
It is a further object of the present invention to provide an improved composite beam structure that overcomes the shortcomings of the prior art.
In accordance with the objects of the invention, a composite beam structure is provided, the beam being suitable for use in connection with a pulp machine, board machine or paper/board finishing device. The beam includes two parts, a first semicircular part and a second strait plate-shaped portion, to which the first portion is joined. The semicircular part is advantageously made by cutting the same from a tube constructed from a fiber tape material using a pultrusion, or pultrusion method. A plate made, for example, by lamination is fixed to the semicircular part. The end of the plate is at an angle with respect to the rest of the plate frame. The angle is chosen so as to be suitable for the location of use. A holder is further attached to the laminated plate, to which holder are also attached means to be placed against the face of a roll for cleaning the roll face or for applying a coating material, or measurement devices in which connection the beam serves as a measuring beam. In addition to lamination, the straight plate portion can also be made by extrusion or by pultrusion. The composite structure provides the following advantages:
no thermal insulation is needed for preventing thermal warping,
the natural frequency of the beam is higher than that of steel with the same dimensions, with the result that the beam is smaller,
oscillation of the beam is easier at higher frequencies because of the small mass of the beam,
smaller deflection because of the beam""s own weight, in which case there is no need for so-called xe2x80x9ccrowningxe2x80x9d of the head.
The invention will be described in detail with reference to some preferred embodiments of the invention illustrated in the accompanying drawings. However, the invention is not confined to the illustrated embodiments alone.